1. Field of Invention
The present invention relates to a fan and an impeller thereof with a self heat-dissipating function.
2. Related Art
Since electronic products are developed towards high performance, high frequency and minimization, heats generated by the electronic products are accordingly increased. The generated heats may affect the reliability and lifetime of the electronic products, so that the heat dissipation thereof has become an important issue. It is a common solution to use a fan to dissipate the heat. However, when the fan operates, the coils thereof will be heated to high temperature, which may be harmful to the bearing or affect the motor efficiency.
As shown in FIG. 1, a conventional fan 1 includes a motor 10 and an impeller 11 driven by the motor 10. The impeller 11 is instituted by blades 111 and a hub 112 for accommodating the motor 10. The hub 112 has several holes 113 formed on the top portion thereof for indusing airflows from outside of the hub 112 to the interior of the fan 1 through the holes 113. The dotted arrow lines shown in FIG. 1 indicate the direction of the airflows.
Such conventional fan 1 mainly utilizes the airflows to carry the external cold air via passing through the hub 112 with the holes 113 for dissipating the internal heat. However, the flow of the cold air may be counteracted by the raised the hot air, thereby decreasing the heat dissipation efficiency. In addition, the airflows also carry dusts, foreign matters and moistures into the fan 1, so that the motor and internal components may be easily damaged.